The present invention relates to an electrochromic element to be used in the control of luminous energy and in a display, and particularly to a whole solid type electrochromic element.
The phenomenon that an electrolytic oxidation or an electrolytic reduction reversibly occurs upon applying a voltage to be reversibly colored or discolored refers to electrochromism. An electrochromic (hereinafter sometimes referred to as xe2x80x9cECxe2x80x9d) element utilizing such a phenomenon has been used in an element for regulating luminous energy (e.g., an antiglare mirror, a dimmer glass, and a meter, a brightness control element, e.g., an EL display element), number display utilizing a segment, and a display element such as an electrochromic display. Depending upon the state of EC layers constructing the EC element, the EC element can be roughly divided into a liquid type, a gel type, and a whole solid type. Amongst them, the element in which all the EC layers including an ion conductive layer are composed of thin solid films is the whole solid type EC element.
FIG. 9 shows a typical configuration of the whole solid type EC element. Outlining the configuration, on a transparent substrate 1 are provided a lower electrode layer 2, and an EC layer 3 comprising an oxidative chromic film which colors due to the oxidation reaction, a solid electrolyte film serving as an ion conductive film and a reductive chromic film which colors due to the reduction reaction, and an upper electrode film 4 in this order. In the case of a reflective type EC element, either of the lower electrode film 2 and the upper electrode film 4 is transparent, while in the case of a transmission type EC element, both of the lower electrode film 2 and the upper electrode film 4 are transparent. These films are usually sealed with a sealing resin (not shown) as a whole, and a sealing glass (not shown) is adhered on the rear surface of the sealing resin for chemical and physical protection.
When a voltage is applied between the lower electrode film 2 and the upper electrode film 4 of the EC element thus produced, an electrically chemical reaction occurs within the EC layer 3, which is chromic layer, to color the element. Upon applying a voltage in a reverse direction to the coloration, the EC element is discolored due to the reverse reaction.
As shown in FIG. 9, with regard to tapping the electrodes in order to connects the lower electrode film 2 and the upper electrode film 4 of the EC element to external wires, the lower electrode film 2 and the upper electrode film 4 are formed with shifting the patterns, whereby the ends of the lower electrode film 2 and the upper electrode film 4 are exposed on both ends of the substrate 1, taking the exposed portion of the lower electrode film 2 as a tapping electrode 2a for the lower electrode film 2, and the exposed portion of the upper electrode film 4 as a tapping electrode 4a for the upper electrode film 4. At present, a manner is applied that external wires are connected to these tapping electrodes 2a and 4a via a clip electrode 5, etc. FIG. 8 shows an example in which this configuration is applied to an automobile antiglare interior mirror, tapping electrodes (not shown) for respective electrode films are provided on two opposite sides 1a and 1b of the substrate 1, and external wires are connected to the tapping electrodes via a clip electrode 5 and a conductive wire 5xe2x80x2, respectively. From the viewpoint of securing sufficient response as the antiglare element through the lower electrode film 2, the upper electrode film 4, and the like, such a manner has been applied that a tapping electrode for one electrode film is provided on two or three sides of the substrate, and a tapping electrode for the other electrode film is provided on the other side (Japanese Patent Laid-Open Publication No. 8-229856).
However, the above manner has the disadvantage, for example, in the case of the automobile antiglare mirror, that there are tapping regions on a plurality of sides of the substrate, and the areas of the tapping electrode regions are large, decreasing an effective area which can be come out on the mirror and narrowing the effective view field which can be secured. Also, the problem occurs that the length of the wire becomes large.
When a luminophor element is piled up on the EL element in order to control the brightness of a luminophor element (electroluminescence (EL) luminophor, LED, Braun tube, various displays, etc.), the problem sometimes occurs that tapping of the electrode is provided only with difficulty depending upon the construction of the luminophor element, e.g., a luminophor element which requires an electrode-tapping only from one side.
In the present invention, coming up with various technical ideas for the film formation configuration and the positions of the electrodes, and as a result, an effective area for the coloration and discoloration of the EC element can be widened without impairing the performance of the EC element, which can never attain the prior art, by providing the tapping electrode only on one side. By intensively arranging the tapping electrode on one side, the wiring becomes easy and the length of the wiring can be shortened.
For example, in the case of the automobile antiglare mirror, the effective area for the mirror portion is increased to widen the effective view field, contributing the safety. What is more, a mirror ring which covers the outer circumference of the mirror can be made slim, enhancing a smart looking from the viewpoint of the design. Also, in comparison with the case where the electrode tapping is carried out on two or more sides, the present invention makes it possible to secure the same effective visibility with a lightweight.
Also, for example, if the EC element of the present invention is used for controlling the brightness of the luninophor element, by intensively arranging the electrode tapping on one side, the electrode can be tapped only within a restricted space, making it possible to control the brightness of luminophor element which requires the tapping of the electrode only from one side (such as meters and EL display elements), such a control being difficult in the prior art.